Ay mama, kung uncertain ka sa dates, best talaga na i-check mo with your OB para makuha ang accurate due date through ultrasound, mahirap mag-calculate kung hindi ka sure kung spotting o actual period yun noong February! The pelvic pain you're describing sounds like it could be normal ligament stretching, pero since may back pain din, I'd really suggest checking with your doctor to make sure everything's good, especially para ma-confirm din ang dating ng pregnancy mo. Maraming mums din namin ang nakaranas ng similar pains pero safer talaga pag confirmed na ng doctor na normal lang.